Even the unusual particles are community content now. I wonder how long it'll be until valve don't need to make any content themselves whatsoever.

I really don't see a problem with that. I like that valve has supported the community contributors the way they have, there are some really fantastic community hats and weapons in game and lots more stuff that has been created that I hope they'll eventually add. There are many great modelers out there that have created some incredibly high quality stuff yet only a handfull of them will ever see their items in game officially, so I hope they keep the community content coming because I for one think its awesome.